Method of forming a pressed metal article



H. G. CARLSON. METHOD OF FORMING A PRESSED METAL ARTI CLE. APPLICATIONFILED SEPT. 17, 1918.

1,889,739. Patentedsept. 6, 1921.

H. G. CARLSON. METHOD OF FORMING A PRESSED METAL ARTICLE.

APPLICATION FILED SEPT. 17, 1918. 1,389,739.

Patented Sept. 6, 1921.

- UNITED STATES PATENT OFFICE.

HJALMAR G. CABLSO'N, OF WORCESTER, MASSACHUSETTS, ASSIGNOR, BY MESNEASSIGNMENTS, TO ROCKWOOD SPRINKLER COMPANY OF MASSACHUSETTS, OFWORCESTER, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

METHOD OF FORMING A PRESSED METAL ARTICLE.

Specification of Letters Patent.

Patented Sept. 6, 1921.

Application filed September 17, 1918. I Serial No. 254,481.

To all whom it may concern:

Be it known thatI, HJALMAR specification.

This invention relates to a method of pro- :ducing from a flat sheetmetal blank a tubular article having one end of materially thicker stockthan the other, but integral with the tubular portion. Such an articlecan be formed for any desired purpose.

The invention involves. the process of gradually producing such anarticle by a series of cold'drawlng operations and doubling over its endin dies so as to render the end portion of more than double thickness asdescribed. Further objects and advantages of the invention will appearhereinafter. 1

Reference is to be had to the accompanying drawings, in which-- Figure 1is an edge view of a circular blank of soft sheet metal from which thearticle is to be produced, and

Figs. 2 to 12 .inclusive are. longitudinal central sectional views ofthe blank in several stages of its roduction, the order of the stepsbeing in icated by the numerals designating the several figures, Fig. 12showing'thei completed article so far as the metal drawing operationsare concerned.

The invention is shown herein as being employed for the prqiuction of acombination booster casing and adapter for a shell, the adapter beingintegral with the booster casing'and being formed with a doubled overexternal flange as indicated above. This is a cold drawn article, but ofcourse the metal is annealed as many times as may be necessary. Thearticle, of course,.can be made in any desired size or shape, but theoneillustrated is made from a circular blank 10 0f annealed sheet stockas indicated in Fig. 1. This is shaped by dies to produce by the firstoperationa flanged cup such as indicated in Fi 2. By this operation thecenter of the b ank is drawn out to forma central cup-shaped portion 12having a circumferential flat edge 11 at the open end The.

GfCAnLsoN, a citizen of the United States, residing at.

diameter of the blank is reduced by this operation and the metal is onlyslightly thickened at the edge.

The second operation, the result of which isindicated in Fig. 3 is shownmainly for the purpose of flattening and thinning the base 13 of theblank. The thinning however may be omitted in some classes of work. Theinternal and external diameters of the walls between the base and edgeflange 11 are reduced by this operation and the length of the cylinderincreased. The thickness of the flange 11 is unchanged although as thisIflange is not'held between flat surfaces, it

becomes curved.

The third operation changes the shape of the blank shown in Fig. 3 tothat shown in Fig. 4:, in which the edge flange 11 is not materiallyincreased in area. The internal and external diameters of the tubularportion are materially reduced,the thickness of the stock everywhereremaining substaki tially the same.

By the next operation indicated in Fig 5 again the only change producedis the reduction in diameter of the cylindrical portion of the blank andlengthening it.

The next operation also is for a similar purpose, the diameter beingreduced slightly and the length increased. This result is indicated inFig. 6.

It will be seen that Figs. 4, 5 and 6 represent the results of threeoperations, each of which has for its object merely the reduction indiameter and the increase in length of the cylindrical portion of theblank. No change in thickness is intended anywhere, but it is found thatthe diameter of the flange 11 may be increased slightly, and of courseits width is materially increased. 2

The next operation, the result of which is shown in Fig. 7 also involvesthe lengthening of the tubular portion, but by the reduction of its endonly. The open end 141 of the tube near the flange 11 is left in thesame condition as in Fig. 6, but the closed end is drawn out between thedie and the flange 11 has a wavy shape, a circular corrugation beingformed in it. This is provided to store a surplus of metal here so thatin performing the next operation shown in Fig. 9 there will be stock toforce into the square corners of the dies and fill them up to producethe shoulder 17. The edge is now trimmed off to a true cylindricalsurface to exactly fit the dies shown in Fig.8 and hold the metal sothat the square shoulder can be formed by means of these dies. Theflange 11 is flattened out, or its flattening completed, between theflat die plates. When the cup leaves the dies shown in Fig. 8 itsshoulder 15 is nearly square and its flange is flat. Preferably acorrugation 18 is then formed in the edge of the flange to produce theshape shown in Fig. 9.

Having brought the blank tothis form, the thin tubular portion 16 is inits final shape as is also the thickened portion 14 at the base. Theflange 11 is the only thing that now remains to be shaped, and this isbent over by forcing it through a die and assumes the form shown in Fig.10. It now constitutes an external rim 11 of circular shape spaced fromthe inner wall 14.

Two operations in forming dies force this rim 11 up against the surfaceof the wall 14. The results of these operations are shown in Figs. 11and 12. Fig. 11 shows the rim drawn in and Fig. 12 shows it upsetagainst the wall 14. In the final condition this rim 11 constitutes anintegral external wall of conical shape connected with the internal wall14 at the end, which in turn is integral with the tubular casing 16below. It is to be observed that the upsetting causes both walls 11 and14 to be materially thicker than the wall 16. I have shown the rim 11 asextending beyond the shoulder 15 which connects the tubular casing 16with the inner wall 14.

A feature shown in Fig. 12 is the anchoring of the rim 11 to the wall 14on the out side. As the rim 11 is upset longitudinally and is forced inover the shoulder 17, its inner surface assumes a barrel shape and givesthe wall 14a corresponding form fitting in it. This anchors thetwo'parts together. Thus, if any weakness develops where the rim is bentover, it tends to be compensated for by this construction. WVhen itdesired to still further strengthen this part of the article thecorrugation 18 is pro vided. This furnishes surplus metal for forming asolid projection 19 which is drawn in behind the shoulder 17 andabsolutely prevents the fracture of the article where the rim is turnedover. It also makes the rim 11 very thick and rigid so that it willstand threading without being unduly weakened.

The external conical surface of the rim 11 is to be provided with a pipethread if the device is to be used as an adapter. The inner wall also isto be provided with an internal screw-thread for receiving an internalelement whenever that is desired. The part of the rim at the end beyondthe screw thread is shown as octagonal in form so that it may be screwedin by a wrench as usual. This is formed in the last operation.

It will be seen, therefore, that by a series of operations such asdescribed above, a flat blank of sheet stock can be converted into atubular structure having comparatively thin end and side walls andprovided with a'base having walls of double thickness, each of thelatter walls being of greater thickness than the original blank, andthat this furnishes a solid and firm base integrally connected with thetubular casing which it supports. Such an article can be used as acombined adapter and booster casing in a shell, but the process can beused for manufacturing articles of other various kinds requiring similarproperties.

I am aware, of course, that the exact number of steps set forth hereinis not absolutely essential to all kinds of articles that can be made bythis process; for example, the three steps represented by Figs. 4, 5 and6 can be replaced by two or four steps if the particular conditionsrequire it, and the same is true of the operations represented by Figs.7, 8 and 9. Moreover in making adapters for other shells modificationswithin the skill of any person skilled in the art may be made in thisprocess without departing from the scope of the invention as expressedin the claims. Therefore, I do not wish to be limited in these respects,but what I do claim 1S 1. The method of making an article having ahollow closed end and a'double-walled open end, which consists indrawing out a flat blank of cold drawn sheet stock into an elongatedtubular shape with one end closed and reduced in thickness and the otherend having a circular flange surrounding it, then reducing andelongating the closed end only of the blank by a series of steps, andfinally turning over the flange so as to envelop the adjacent wall ofthe blank.

2. The method of making an adapter and booster casing whichconsists indrawing out a flat blank of sheet stock intoan elongated tubular shapewith one end closed and the other end having a circular flangesurrounding it, then reducing and elongating the closed end of the blankby a series of drawing operations, leaving the open end of that part ofthe blank unreduced in diameter and thickness, and turning over theflange into contact with the adjacent convex wall of the blank beyondthe unreduced portion to hold the two parts together.

3. The method of drawing sheet metal stock which consists in drawing outa projection from a blank, leaving the open edge in the form of asurrounding flange, forming a shoulder on the projection, doubling overthe flat flange to form a rim surrounding the open end of saidprojection, and finally forcing the rim against the wall whichconstitutes theend of the projection and behind said shoulder.

4. The method of cold drawing sheet metal which consists in drawing outa tubular projection from a flat circular blank, leaving the open edgein. the form of a surrounding flange, annealing it at suitableintervals, elongating and reducing in diameter the tubular pro ection,thereafter maintaining the portion of this tubular projection near theopen end in substantially uniform condition, and while in that conditiondrawing out the closed end of the same so as to increase its length andreduce its diameter and thickness, forming a shoulder at the end of thethicker portion of the same, doubling1 over the flange so as to form arim surrounding the thick portion and projecting beyond said shoulder,and finall forcing the same against the inner wall to ring the rim atits edge beyond the shoulder, u setting the rim and giving it a conicals ape outside.

5. The method of drawing sheet metal stock which consists in drawing outin dies a central projection from a flat circular blank, leaving theopen edge in the form of a surrounding flange, progressively drawing outthe closed end so as to increase its len th and reduce its diameter andthickness at t e end, forming a shoulder on the thicker portion of thesame, doubling over the flat flange, and finally forcing the sameagainst the inner relatively thin wall which constitutes the end of thetubular part and over said shoulder.

6. The method of drawing sheet metal which consists in drawing out indies a central projection from a flat circular blank so as to leave theopen edge in the form of a surrounding flange, forming a circumferentialshoulder on the projection, doubling over the flange, and finallyforcing the same toward the inner wall to bring the external wall orflange at its edge beyond the shoulder, and upsetting the projectingedge against said shoulder.

7. The method of cold drawing sheet stock which consists in drawing outin dies a central projection from a flat circular blank so .as to leavethe open edge in the form of a surrounding flange, progressivelyelongating and reducing in diameter the central portion thereof to forma tubular shape, maintain ing the portion of this tubular part near theopen end in substantially uniform condition, while in that conditionprogressively drawing out the closed end of the same so as to increaseits lengthand reduce its diameter, forming a shoulder on the thickerportion of the same, doubling over the flange, and finally forcing thesame against the thick wall, forcing its end over said shoulder andupsetting it lon itudinall to give the inner surface of the ange an theouter surface of the thick wall an interlocking convex or barrel shape.

In testimony whereof I have hereunto aflixed my si nature.

DHJALMAR G. CARLSON.

